1. Field of the Invention
The present invention relates to a light emitting diode package having a lens structure for lateral emission of light, and more particularly, to a light emitting diode package which is easily manufactured by separately molding an upper lens and a lower lens and binding them together, and is efficiently installed.
2. Description of the Related Art
With recent developments in electronic devices industry, Liquid Crystal Displays (LCDs) are drawing attention as the next-generation display apparatus. An LCD does not generate light on its own, and thus typically requires a backlight module for generating light at the back of an LCD panel.
FIG. 1 is a sectional view illustrating an example of a conventional side-emitting Light Emitting Diode (hereinafter, referred to as LED) used in an LCD backlight module, disclosed in U.S. Pat. No. 6,679,621.
Referring to FIG. 1, the LED lens 10 disclosed in the above document includes an upper part having a reflecting surface I and a refracting surface H, and a lower part having a refracting surface 12. In three dimensions, the LED lens 10 is shaped symmetrically about an axis A.
In this LED lens, light emitted from a focus F is reflected on the reflecting surface I and then exits through the refracting surface H to the outside, or light exits directly through the refracting surface 12. As a result, light is hardly emitted upward but emitted laterally about the axis A.
However, the above conventional LED 10 has following problems.
First, it is difficult to mold the LED lens 10. That is, it is difficult to precisely form a connection part L connecting the refracting surface H and the lower refracting surface 12, and an inner vertex P where the reflecting surfaces I converge. Also, there may be lines formed on or in the proximity of the connection part L of the lens 10.
Further, an additional process is required to prevent air bubbles while filling in a space S housing an LED chip denoted by the focus F with resin.
This process is explained with reference to FIGS. 1 and 2. First, the LED lens 10 is placed upside down and transparent resin 24 is poured to fill in the space S of the LED lens 10. In the meantime, the LED chip 22 is mounted on a substrate 20, and the coupled structure is attached to the upside-down LED lens 10 such that the LED chip 22 is positioned inside the space S of the LED lens 10. The final structure is overturned again into the original position, which is shown in FIG. 2.
However, in this case, the air bubbles produced in the resin 24 in the space S cannot escape, which may degrade optical characteristics of the LED package. In addition, the LED chip 22 is immersed in the resin 24 in the space S, which results in the overflowing resin that is difficult to handle.
Moreover, the LED lens 10 has a complex structure and thus needs to be molded with resin having excellent moldability such as polycarbonate (PC) or polyethylene (PE). However, these kinds of resin are deformed typically at about 150° C., which restricts the process of mounting the package of FIG. 2 on the backlight module. That is, the package should be mounted on the backlight module without any exposure of heat to the lens 10, which complicates the manufacturing conditions.
FIG. 3 illustrates another conventional example with a lens structure improved from that in FIGS. 1 and 2. An LED lens 50 of FIG. 3 has a different configuration of a refracting surface H from that in FIG. 1 in order to increase light emission efficiency. The rest of the configuration except the refracting surface H is substantially identical with that in FIGS. 1 and 2. Also, a pair of leads 64 is added to supply power to the LED chip.
However, as the package of FIG. 3 has the identical basic configuration with that in FIGS. 1 and 2, it is not free from the aforementioned problems regarding its structure and manufacturing processes. Further, the lens 50 has to be made of the same material as the LED lens 10 of FIGS. 1 and 2, which restricts the temperature conditions allowed in the manufacturing processes.